Here's a little gallery.
@elef - can you take a shot or two of the bottom of the keycaps on the wave? I'm really curious to see whether modifying the female end to the cherry MX cross is possible. I have some mutilated keycaps from a Saitek board that I was going to experiment with.
As you can see, the bottom part of the Wave's keys is the same height, and it's the "cap" part that has variable height. That's good, but the rest of the news is less promising. Of course it doesn't have the Cherry "+" shape, and, what's worse, it would take a heroic hack to get it on cherry switches.
For starters, the stem part of the keycap on a Cherry key drops inside the keyswitch housing when the key is pressed. Even if you could hack these caps onto the + shaped stem somehow, it wouldn't work, as the Wave's rectangular stems are too large. They wouldn't fit inside, so you couldn't press the key.
If someone made a Wave-like replacement caps for cherries, I'd certainly buy a set for $50 or $60, but I don't think that's going to happen.
If someone really wanted to do this (and I sort of do), the easiest option would probably be to use epoxy or something like that. Take the keycaps off, make molds with the various shapes and heights, possibly molding directly from the Wave's keys, and add height/slant to the cherry caps that way. They would still be taller than the rest of the keys on the keyboard, but not by that much.
This could possibly be attempted without damaging the either keycap set. Cherry keycaps are 20 GBP a set from keyboardco, so even if you destroy a set, it's not that tragic.